Open nanocavity-assisted Ag@PDMS as a soft SERS substrate with ultra-sensitivity and high uniformity

Abstract

To achieve high sensitivity and uniformity simultaneously in a surface-enhanced Raman scattering (SERS) substrate, this paper presents the preparation of a flexible and transparent three-dimensional (3D) ordered hemispherical array polydimethylsiloxane (PDMS) film. This is achieved by self-assembling a single-layer polystyrene (PS) microsphere array on a silicon substrate. The liquid-liquid interface method is then used to transfer Ag nanoparticles onto the PDMS film, which includes open nanocavity arrays created by etching the PS microsphere array. An open nanocavity assistant soft SERS sample, “Ag@PDMS,” is then prepared. For electromagnetic simulation of our sample, we utilized Comsol software. It has been experimentally confirmed that the Ag@PDMS substrate with silver particles of 50 nm in size is capable of achieving the largest localized electromagnetic hot spots in space. The optimal sample, Ag@PDMS, exhibits ultra-high sensitivity towards Rhodamine 6 G (R6G) probe molecules, with a limit of detection (LOD) of 10−15 mol/L, and an enhancement factor (EF) of ∼1012. Additionally, the substrate exhibits a highly uniform signal intensity for probe molecules, with a relative standard deviation (RSD) of approximately 6.86%. Moreover, it is capable of detecting multiple molecules and can perform real detection on non-flat surfaces.

Polyethyleneimine-assisted formation of Ag–SiO2 hybrid microspheres for H2O2 sensing and SERS applications

“…However, a double monolayer Ag@SiO 2 and open nanocavity assistant soft SERS sample Ag@PDMS were able to show enhancement factors of ∼10 13 and 10 12 , respectively. 75,76 Although these materials offer significant advantages in terms of AEF, there are certain limitations to the methods used for synthesizing nanocavity-assisted soft SERS samples, as the technique used is a liquid–liquid transfer method. In the liquid–liquid transfer method, a rigid substrate is used and the fabrication method involves multiple steps, which makes it complex and cumbersome compared to our synthesis methodology, which is a one-step, cost-effective approach.…”

Flexible Large-Area Surface Enhanced Raman Scattering Substrate Based on Bowl-Shaped Arrays of Au Nanoparticles on PDMS

“…Finally, the PS spheres were removed using heat, and the resulting structure was placed in a 70 °C oven for 6 h before demolding, thus creating the PDMS bowl-shaped nanoarray structure. This step differs from the literature as they employed chemical etching to separate PS and PDMS, which yielded poor results and easily damaged the structure. In contrast, we utilized a thermal demolding method that greatly ensured the integrity of the PDMS bowl-shaped structure.…”

Advancements in mercury detection using surface-enhanced Raman spectroscopy (SERS) and ion-imprinted polymers (IIPs): a review

“…94 Higher-order assemblies can also be achieved through these techniques or decorating the support surface with SERSactive NPs, or modifying the support with materials like graphene. 95 Solid-SERS substrates offer several notable advantages, including convenient handling and transport, enduring stability over time, enhanced reproducibility, and the potential for on-site applications. However, one of the primary challenges encountered in SERS techniques for mercury analysis pertains to the uniformity of the substrate, a factor that can significantly impact the reproducibility and reliability of sensing results.…”

“…94 Higher-order assemblies can also be achieved via these techniques or decorating the support surface with SERS-active NPs, or modifying the support with materials such as graphenes. 95…”